Recent years have seen the widespread use of a digital camera that uses an imaging element such as a CCD (charge coupled device) or CMOS (complementary metal-oxide semiconductor) sensor to convert an optical image into an electric signal and to record the electric signal in a digitized form. In a digital camera configured as above, there is a need not only for increasing the number of pixels of a CCD or CMOS sensor but also for improving the performance of a lens barrel that forms an optical image on such an imaging element. Specifically, there is a need for a lens barrel incorporating a higher-powered zoom lens system.
Meanwhile, in the field of a digital camera, there is a demand for miniaturization of a body in order to improve portability. To this end, there is a need for miniaturization of an imaging apparatus including a lens barrel and an imaging element, which is believed to contribute greatly to miniaturization of the body. In an effort to achieve the above-described miniaturization of an imaging apparatus, a so-called bending optical system has been proposed, which achieves the miniaturization of the apparatus without changing the length of an optical path by bending a zoom lens system at some point along the optical path.
For example, Patent Document 1 discloses a bending optical system in which an optical path is bent using a reflection mirror. Specifically, a lens barrel disclosed in Patent Document 1 includes on the side of a subject relative to the reflection mirror, a first lens group and a second lens group in this order from the side of the subject, and on the side of an imaging element relative to the reflection mirror, a third lens group and a fourth lens group in this order from the side of the reflection mirror. The first lens group is fixed. The second lens group and the third lens group are movable in an optical axis direction and constitute a zoom lens system in cooperation with each other. The fourth lens group is used for focus adjustment.
Furthermore, Patent Document 2 discloses a bending optical system in which an optical path is bent using a prism. Specifically, a lens barrel disclosed in Patent Document 2 includes a lens group on the side of a subject relative to the prism. The lens group is movable between an in-use position and a retracted position in an optical axis direction. Moreover, the prism is movable so that a space for accommodating the lens group is secured when the lens group is in the retracted position.
Furthermore, Patent Document 3 discloses a configuration of a lens group used in a bending optical system.
However, in order to simultaneously meet the rising demands for the realization of a high-power zoom lens system and the achievement of miniaturization, further improvement is required.
Specifically, in each of the configurations disclosed in Patent Documents 1 and 2, respectively, it is difficult to construct a high-power zoom lens system while achieving miniaturization of the apparatus. Moreover, also when adopting the lens configuration disclosed in Patent Document 3, Patent Document 3 is disadvantageous in that it does not disclose any configuration for achieving miniaturization of the apparatus.
Meanwhile, generally, in the case of a miniaturized imaging apparatus or in the case of including a high-power zoom lens system, there is a need for preventing blurring of a photographed image (image blurring) from occurring, which mainly is due to camera shake or the like.
FIG. 18 is an exploded perspective view of an image stabilizing device of the prior art (see Patent Document 4). In the image stabilizing device shown in FIG. 18, a second lens group 101 is held by a lens frame 102. The lens frame 102 is supported movably by guide shafts 103 that guide movement in a pitching direction and in a yawing direction. Further, the lens frame 102 is provided with coils 104a and 104b for driving the lens frame 102 in the pitching direction and in the yawing direction, respectively. On a fixed base 105, magnets 106a and 106b are provided so as to be opposed to the coils 104a and 104b, respectively. When the coils 104a and 104b are energized, driving forces are generated in the respective directions. The second lens group 101 is driven in the pitching direction and in the yawing direction by the driving forces generated in the coils 104a and 104b, respectively. The amount of shake of a lens barrel is detected by angular velocity sensors 107a and 107b, and based on a detection signal obtained as a result of the detection, the coils 104a and 104b are energized so that image stabilization is performed.    Patent Document 1: JP 11(1999)-258678 A    Patent Document 2: JP 2003-169236 A    Patent Document 3: JP 2004-102089 A    Patent Document 4: JP 2000-75338 A (FIG. 4)    Patent Document 5: JP 7(1995)-5514 A (FIGS. 6 and 8)